Electron tube



Aug. 3, 1948.

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Intumsoibroadinciusiomourtuhecomprises ananodeaconcentriccathotkstem andanintermediate grid terminal member, all arranged coaxial on the envelope, Theanodehas an inmitwardiynl'ojectin portionilcarryingtheuookrlt. Thisanodeunttis generally wlindricalinshpeclncmtri withthelongimallxisofthetuhgandiasccuredtosupport Lubyacopperbrueilattherimotwm a 2 path. Races I is preferably cylindrical and is coaxial with the anode.

Heat is conducted away from the active portion of the anode by the outwardly projecting north; I I, which portion iorms the core of cooler l2. Anode portion II is preferably cylindrical and of suflicient cross-sectional area to provide for the necessary heat flow. Cooler I! may be oi any suitable construction, such as one having radial fins it secured to a sleeve [8 attached to anode portion H.

The tube is exhausted through a metal tubulation i1 secured to the end of anode projection ii, This tribulation communicates with a passage it into the anode opening into anode recess After exhaust, the tube issealed by mechanicaily pinching oil thetubulation at tip it. By surrounding tubuiation l1, thecooler performs the additional function 01' providing a protective closure for the tubulation.

Grid terminal member 4 is preferably tubular and is coaxial with the anode, It has a flange 2! to which glass body section 2 is sealed. Grid 21 is preferably cylindrical with vertical bars secured at the top/to a cap 23 and at the bottom to a conical bracket 24 having a cylindrical sleeve 26 fitted into terminal member 4. This grid assembly is inserted through the open end of memher 4, and is secured by spot welding to reduced neck portion 21 of member 4. Theseparts are careiuliy shaped as to diameter so as to align the grid within the anode recess. Member I, being connected to the grid, thus functions as the grid terminal.

Cathode stem 28 is also coaxial with the anode, and projects into tubular member 4 from which The stem comprises a pair of concentric stem members including an outer tubular part 29 and an inner rod-like part Ii. These stem parts are joined by a glass head I! sealed between rod 3i and the lower end of a sleeve II, which sleeve is fitted into tubular stem part II and secured thereto by braze I4.

The cathode comprises a can-shaped element It having a cylindrical side wall carrying the active cathode coating. This coating may be of the usual oxide type commonly employed with indirectly heated cathodes. Cathode element It extendsconcentrically within the grid and the anode recess. It is Supported by and electrically connected to outer stem member I! by bracket arms 31. The cathode heater comprises a spiral llconnectedat oneendtotheinnerstemmemher and at the other end to base plate I! of the cathode element. Heating current may thus be 3 supplied to the heater through the stem members.

The cathode and its stem structure is supported by a U-shaped sleeve fitted into tubular member 5 and having an outer flange M and an inner flange B2. A vitreous ring or washer 43 is sealed between outer stem member 29 and inner flange 42 of the supporting sleeve. Sleeve Ill-42 abuts sleeve 26 so that the latter serves as a spacer and positioning stop for the cathode unit. Final braze 44 is made at the outer edge of flange M and the adjacent rim of tubular member 4.

We claim:

1. An electron tube comprising an envelope having a recessed anode at the upper end and a cathode stem at the lower end, said stem comprising an outer tubular member and an inner prong member, a grid terminal ring interposed in the envelope wall between the outer stem member and said anode and providing a cylindrical contact surface, the lower portions of the stem members projecting externally of the envelope and providing cylindrical contact surfaces coaxial with that of said grid terminal ring, the cylinders defined by said contact surfaces having different diameters of which the inner stem member is the smallest the outer stem member is next largest and the grid terminal ring is the largest, a cathodeelement extending into the anode recess and connected to one of the stem members, a heater for the cathode element connected to the stem members, and a grid disposed about the cathode element and connected to said grid terminal ring.

2. An electron tube comprising an envelope having a recessed anode at the upper end and a cathode stem at the lower end, said stem comrisin an outer tubular member and an inner prong member, a grid terminal ring interposed in the envelope wall between the outer stem member and said anode and providing a cylindrical contact surface, the lower portions of the stem members projecting externally of the envelope and providing cylindrical contact surfaces coaxial with that of said grid terminal ring, the

cylinders defined b said contact surfaces havin diflerent diameters of which the inner stem member is the smallest the outer stem member is next largest and the grid terminal ring is the largest, the envelope wall being joined to the tubular stem member above its cylindrical contact surface, vacuum-tight sealing means disposed between' the stem members and joined to the inner prong member above its cylindrical contact surface, a cathode element extending into the anode recess and connected to one of the stem members, a heater for the cathode element connected to the stem members, and a grid disposed about the cathode element and connected to said grid terminal ring.

WILLIAM W. EITEL.

JACK A. McCULLOUGH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED s'rams PATENTS Number Name Date 2,107,945 Hull et al. Feb. 8, 1938 2,190,511 Cage Feb. 3, 1940 2,267,128 Mouromtseff et al. Dec. 23, 1941 2,310,936 Chevigny Feb. 16, 1943 2,367,311 Bondley Jan. 16, 1945 2,368,535 Gaudenzi Jan. 30, 1945 

